Questions: According to the Chapter 3 presentation in Brightspace neurons are "green" because they look green when viewed with a CAT scan. recycle neurotransmitters by reabsorbing what is not used in the synapse. are green if they are not myelinated. turn green when deprived of oxygen.

The answer is the second one: recycle neurotransmitters by reabsorbing what is not used in the synapse.

Explanation for each option:

1. Look green when viewed with a CAT scan: This is incorrect. Neurons do not appear green in CAT scans. CAT scans typically produce images in shades of gray, not color.
2. Recycle neurotransmitters by reabsorbing what is not used in the synapse: This is correct. Neurons are often described as "green" in the sense that they are efficient and recycle neurotransmitters through a process called reuptake.
3. Are green if they are not myelinated: This is incorrect. The color of neurons is not determined by whether they are myelinated or not. Myelination affects the speed of signal transmission, not the color.
4. Turn green when deprived of oxygen: This is incorrect. Neurons do not change color to green when deprived of oxygen. Lack of oxygen can cause damage or death to neurons, but it does not cause them to turn green.

Summary: Neurons are described as "green" because they recycle neurotransmitters by reabsorbing what is not used in the synapse.